The present invention relates to tissue fixation plate system and more specifically to such systems having a primary fixation plate with a depending graft retention loop and a longer auxiliary fixation plate.
Tissue fixation plates fix tissue to bone adjacent a bone tunnel. One common usage occurs in Anterior Cruciate Ligament (ACL) reconstruction. A bone tunnel is formed through a femur. It comprises a graft channel wide enough to accommodate a replacement graft tissue and terminates in a smaller passing channel that exits through the cortical bone and is wide enough to pass the fixation plate. The graft is carried by a loop depending from the fixation plate and the plate is guided lengthwise up through the bone tunnel whereupon its orientation is flipped approximately ninety degrees to rest against the surface of the femur and be thus prevented from passing back through the tunnel. Examples of such flipping-type fixation devices are disclosed in U.S. Pat. Nos. 5,306,301 and 5,645,588 incorporated herein by reference.
If the graft channel is drilled too deeply there may be no passing channel or insufficient bone thickness to support a preferred size of fixation plate. A surgeon may also desire to prepare a single diameter bone tunnel. In each case a larger fixation plate will be required for proper fixation. An expanded size accessory plate is typically employed having a length exceeding that of the primary fixation plate and having an upper recess into which the primary fixation plate fits.
Current accessory plates are difficult to use because of the difficulty in attaching them seamlessly to the primary fixation plate. Often the graft must first be removed from the graft loop so that the graft loop can be threaded into a hole through the accessory plate that accepts the loop. Then, the graft must be re-loaded on the graft loop prior to the construct being used. Also, the existing plates do not tend to interconnect well.
Other solutions include simply using a larger fixation plate, but again, the graft must be offloaded from the original loop and then loaded onto the second plate's graft loop.